Conversion of hydrocarbon oils



Oct. 27, 1936. J. c. MQRRELL I CONVERSION OF HYDROCARBON OILS FiledMarch 12, 1931 FURNACE lNVi-INTOR JACQUE C. MORRELL 5 MQ ATTOR EYPatented Oct. 27, 1936 UNITED STATES PATENT OFFICE 7 2,058,488CONVERSION OF HYDROCARBON oms ware Application March 12, 1931, SerialNo.522,147 5 Claims. (01.196-51) This invention relates to the treatment ofhydrocarbon oils and refers particularly to the conversion of relativelyheavy oils into lighter and more valuable products. a

- The primary principles of the present invention comprise subjecting araw oil charging stock to conversion conditions and simultaneouslysubiecting a different raw, oil charging stock together with refluxcondensate from the system to independently controlled conversionconditions in the same cracking system. The secondary charging stock maybe within the boiling range of gasoline and may be treated specificallyto reform the same for the purpose of improving its antiknock rating.

In its more specific embodiment the invention may comprise subjecting araw oil charging stock to conversion conditions in a heating element,introducing the heated products into an enlarged reaction zone,withdrawing both liquid and vapors simultaneously'from said enlargedreaction zone at a point relatively remote from the point ofintroduction and introducing them into a separate enlarged zone ofvaporizing chamber preferably maintained under reduced pressure and inwhich vapors and liquid may be separated, withdrawing vapors from, saidvaporizing chamber and subjecting them to fractionation,subjecting therelatively light fractionated vapors to condensation and cooling andcollecting the products, withdrawing the relatively heavy insufilcientlycon-- verted components of the vapors subjected to fractionation fromthe fractionating zone and subjecting them together with a separate rawoil charging stock to independently controlled conversion conditions ina separate heating element and introducing the heated oil from saidseparate heating element into the aforementioned vaporizing chamber orinto the reaction zone or partially to both.

As a feature of the present invention all or a portion of the refluxcondensate from the fractionator of the system instead of passingthrough the heating element in which the secondary charging stock is fedmay be introduced into the stream of heated oil discharging from saidheating element to cool said stream of heated oil to the desired degreeprior to its further treatment in succeeding portions of the crackingsystem.

As another feature of the invention, conditions may be so controlled inthe vaporizing chamber or enlarged zone of reduced pressure that eithera liquid residual product, a carbonaceous residual material or a productof intermediate nature such as asphalt or asphalt-like material may beproduced in this zone.

The attached diagrammatic drawing illustrates one form of apparatusembodying the principles of the present invention. The followingdescription of the drawing embraces also a description of the process ofthe present invention as it may be practiced in the form of apparatushere illustrated. 1

A raw oil charging stock, hereinafter designated for the sake ofconvenience as primary charging stock, may be supplied through line Iand valve. 2 to pump 3 from which it may be fed through line 4, valve 5,line 6 and valve I into heating element 8 or all or a portion of theprimary charging stock instead of passing directly to heating element Bmay pass from pump 3 through line 9, valves- Ill and II, preheating coilI2, line I3, valve I4, line 6 and valve I to heating element 8.Preheating coil I2 may be located within fractionator I5 and the oil fedtherethrough may be preheated by indirect contact with the relativelyhot vapors in the fractionator. A portion ofthe primary charging stockmay, i! desired,be fed from line Ill through line I6 and valve I1directly into fractionator I5 combining thereinwith the relatively heavycomponents of the fractionated vapors which may be condensed in thiszone and passing therewith to further treatment as will be more fullydescribed later.

Heating element 8 may be located in any suitable form of furnace I8 andthe primary charging stock fed therethrough may be heated to any desiredconversion temperature preferably under a substantial superatmosphericpressure. The heated oil from heatingelement 8 may pass through line I9and valve 20 to reaction chamber 2| which is also preferably maintainedunder a substantial superatmospheric pressure. The pressure employed inchamber 2I may, however, be either substantially the same or lower thanthat employed in heating element 8. Products from chamber 2I' preferablycomprising both liquid and 'vaporous products may be withdrawn throughline 22 and valve 23 to vaporizing chamber 24 which is preferablymaintained under substantially reduced pressure relative to that em-'ployed in chamber 2 I. Preferably vapors are separated from the residualliquid in chamber 24 and the vapors may pass through line 25, valve 26,heat exchanger 21 and line 28 into fractionator I5. Heat exchanger 21may, of course, be by-passed by well known means, not illustrated, if sodesired. The relatively light desirable components of the fractionatedvapors may pass from fractionator l through line 29 and valve 30, may besubjected to condensation and cooling in condenser 3|, products fromwhich may pass through line 32 and valve 33 to be collected in receiver34. Uncondensable gas may be released from receiver 34 through line 35and valve 36. Distillate may be withdrawn from the receiver through line31 and valve 38. A portion of the distillate from receiver 31 may, ifdesired, be recycled, by well known means not illustrated in thedrawing, to fractionator to assist fractionation of the vapors in thiszone.

A separate charging stock, hereinafter designated for the purpose ofconvenience as secondary charging stock, may be supplied through line 39and valve 40 to pump 4| from which it may be fed through line 42, valve43, heat exchanger 21, line 44, valves 5| and 45, line 46 and valve 41into heating element 48, which may be located in any suitable form offurnace 68. Preferably this secondary charging stock is lighter incharacter than the primary stock and may comprise hydrocarbons withinthe boiling range of gasoline which are treated to reform them or toimprove their anti-knock property. All or any desired portion of thesecondary charging stock may, of course, be diverted from heat exchanger21 and passed from line 42 through line 49 and valve 50 into line 44 andthence to heating element 48, as

be preheated by indirect contact with the relatively hot vapors passingfrom chamber 24 to fractionator l5. It will be understood that-thesecondary charging stock may, if desired, be preheated by any other wellknown means.

The relatively heavy insuficiently converted components of the vaporscondensed in fractionator l5 may pass through line 52 and valve 53 topump 54 from which they may be fed through line 55, valve 56, line 46and valve 41 into heating element 48 together with the secondarycharging stock introduced into this heating element, as alreadydescribed. All or any desired portion of the reflux condensate fromfractionator l5 may, if desired, be diverted from line 55 through line51 and valve 58 into line 59 to cool the stream of heated oil dischargedfrom heating element 48 to the desired temperature prior to itsintroduction into subsequent portions of the system. The oil dischargedfrom heating element 48 passes through line 59 and may be directedeither through valve 60 into chamber 24 or through line 62 and valve 63into chamber 2|, or, if desired, a portion of the heated oil may bedirected to each of these zones.

Conditions may be so regulated in chamber 24 that a liquid residualproduct or ac'a'rbonaceous residual material or a product ofintermediate nature such as asphalt or asphalt-like material may beproduced in this zone. Residual liquid, if produced, may be withdrawnfrom chamber 24 through line 64 and valve 65. In case a carbonaceousresidual material is produced it may be allowed to collect withinchamber 24 to be removed after the operation of the process isdiscontinued or, if desired, a plurality of chambers such as 24, but nothere illustrated, may be employed and may be operated either alternatelyor simultaneously to permit prolonged operation of the process. In caseasphalt or an asphalt-like material is to be produced in chamber 24 aplurality of such zones are preferably employed. Air, steam, otheroxygen-containing gas or hydrocarbon gas or a combination of any ofthese may be introduced into chamber 24 through line 66 to assist theasphalt making operation. This operation is commonly known as blowingand the chamber in which the asphalt is being blown is preferablyisolated from the remainder of the system during this operation.

Pressures employed within the system may range from atmospheric tosuperatmospheric pressures as high as 2000 pounds or more per squareinch, the preferential range in the conversion zone being between 100and 1000 pounds per square inch. Substantially equalized pressure may beemployed throughout the system or differential pressures may be utilizedbetween the various elements of the system. Preferably reduced pressureis employed in the vaporizing chamber and in the succeedingfractionating, eondensing and collecting equipment. Conversiontemperatures employed may range from 800 to 1200 F. more or less.Preferably the conversion temperatures are between 850 and 950 F. in theprimary heating element and between 900 and 1050? F. in the secondaryheating element.

As a specific example of the operation of the process of the presentinvention such as described and illustrated, a 24-26 A. P. I. gravitytopped crude is the primary charging stock and comprises about 70percent of the raw oil supplied to the process. The primary chargingstock is subjected to a temperature of approximately 910 F. under asuperatmospheric pressure of about 200 pounds per square inch. Thispressure is substantially equalized within the reaction chamber but isreduced in the vaporizing chamber to approximately 35 pounds per squareinch. A secondary charging stock of about 36 A. P. I. gravity andsimilar in characteristics to the reflux condensate from thefractionator of the system comprises about 30 'percent of the total rawoil fed to the system and is subjected together with reflux condensatefrom the fractionator toatemperature of about 960 F. underasuperatmospheric pressure of approximately 300 pounds per square inch.A sufiicient quantity of the reflux condensate is introduced into thestream of heated oil discharged from. the secondary heating element tocool this stream of oil which is directed into the reaction chamber to atemperature of approximately 910 'F. This operation may yieldapproximately 65 percent of motor fuel having an anti-knock valueapproximately equivalent to a blend of 50 percent benzol and 50 percentPennsylvania straight-run gasoline. In addition about percent ofmarketable fuel oil may be produced, the only other products of theprocess being uncondensable gas and a negligible quantity ofcarbonaceous material.

In another operation similar to that above outlined except that the oildischarged from the secondary heating element is not cooled by theintroduction of reflux condensate and is introduced into the vaporizingchamber, a substantially dry carbonaceous deposit may be collected inthe vaporizing zone as the residual product of the system and anincreased yield of motor fuel of somewhat higher anti-knock value maybeproduced. The gas production may alsobe increased.

By employing conversion conditions of an intermediate nature to thosedescribed in the above examples and by blowing the residual product inthe vaporizing chamber, for example, with steam, an asphalt-likeresidual product may be produced accompanied by gasoline yieldsgenerally somewhat lower than those obtained by non-residuumoperation'and somewhat higher than those obtained by operations in whichmarketable fuel oil is produced.

In another operation when the secondary charging stock comprising 40% ofthe total raw oil charge to the system was a Pennsylvania straight rungasoline having an anti-knock value of zero benzol equivalent and whenheated to 1050 F. at a pressure of 100 pounds per square inch in thesecondary heating element discharging the same into the vaporizing zone24 a 90% recovery by conversion or reforming of the gasoline may beobtained with an approximately 50% benzol antiknock value or aniso-octane anti-knock value of approximately 70. The other conditionsmay be the same as in the first example, a yield of approximately 55percent gasoline being obtained from the topped crude making a total ofapproximately based on the combined or total charge.

I claim as my invention:

1. In a process of hydrocarbon oil conversion wherein hydrocarbon oil issubjected to cracking conditions of temperature and pressure in aprimary heating zone and the heated hydrocarbon mass passed to areaction zone, the vapors and non-vaporous material being removed fromsaid reaction zone to a vaporizing zone wherein vapors are separatedfrom non-vaporous material, said vapors being passed to a ,fractionatingzone to condense insufficiently converted fractions thereof as refluxcondensate, the improvement which comprises subjecting reflux condensatefrom said fractionating zone to reconversion conditions in a secondaryheating zone, passing a portion of said reconverted mass to saidreaction zone to commingle with the heated hydrocarbons from saidprimary heating zone, and passing the remaining portion of saidreconverted mass to said vaporizing zone.

2. In a process of hydrocarbon oil conversion wherein hydrocarbon oil issubjected to cracking conditions of temperature and pressure in aprimary heating zone and the heated hydrocarbon mass passed to areaction zone, the vapors and non-vaporous material being removed fromsaid reaction zone to a vaporizing zone wherein vapors are separatedfrom non-vaporous material, said vapors being passed to a, fractionatingzone to condense insuificiently converted fractions thereof as refluxcondensate, the improvement which comprises subjecting reflux condensatefrom said fractionating zone in company with a secondary hydrocarboncharging stock to reconversion conditions in a secondary heating zone,passing a portion of said reconverted mass to said reaction zone tocommingle with the heated hydrocarbons from said primary heating zone,and passing the remaining portion of said reconverted mass to saidvaporizing zone. I

3. In a process of hydrocarbon oil conversion wherein hydrocarbon oil-issubjected to cracking conditions of temperature and pressure in aprimary heating zone and the heated hydrocarbon mass passed to areaction zone, the vapors and non-vaporous material being removed fromsaid reaction zone to a vaporizing zone wherein vapors are separatedfrom non-vaporous material, said vapors being passed to a fractionatingzone to condense insufliciently converted fractions thereof as refluxcondensate, the improvement which comprises passing a portion of thereflux condensate to a secondary heating zone wherein reconversion takesplace, returning said reconverted hydrocarbons from said secondaryheating zone in company with the remaining portion of said refluxcondensate to said vaporizing zonewherein said mixture comrningles withthe heated hydrocarbon mass from the primary heating zone.

4. A hydrocarbon oil cracking process which comprises passing the oil ina restricted stream through a heating zone and heating the same thereinto cracking temperature under pressure, discharging the heated oil intoa reaction zone maintained under cracking conditions of temperature andpressure, removing the vaporous and liquid reaction products as amixture from the reaction zone and introducing the same into aseparating zone maintained under lower pressure than the reaction zone,separating said mixture into vapors and residue in the separating zone,dephlegmating the vapors to condense insufliciently cracked fractionsthereof, passing resultant reflux condensate through a second heatingzone and subjecting the same therein to independently controlledcracking conditions of temperature and pressure therein, delivering asubstantial portion of the thus heated reflux condensate directly fromsaid second heating zone to said separating zone without. prior pas-Sage through the reaction zone, and flnally condensin'g the dephlegmatedvapors.

5. A hydrocarbon oil cracking process which comprises passing the oil ina restricted stream through a heating zone and heating the same thereinto' cracking temperature under pressure,

discharging the heated oil into a reaction zone maintained undercracking conditions of temperature and pressure, removing the vaporousand liquid reaction products as a mixture from the reaction zone andintroducing the same into a separating zone maintained under lowerpressure than the reaction zone, separating said mixture into vapors andresidue in the. separating zone, dephlegmating'the vapors to condensein.- sumciently cracked fractions thereof, passing resultant refluxcondensate through a second heating zone and subjecting the same,therein to independently controlled cracking conditions of temperatureand pressure therein, discharging a portion-of the heated refluxcondensate from the second heating zone into the reaction zone,discharging another portion of the heated reflux condensate into theseparating zone, and finally condensing the dephleginated vapors.

